1. Field of the Invention
The invention in general relates to line pressure probes that are used in line leak detector systems, and more particularly with such a pressure probe which is capable of analyzing the pressure data to provide a pressure signal that is more reliably representative of a link leak than the pressure signals provided by prior art pressure probes.
2. Description of the Prior Art
Line pressure probes have been widely used in the petroleum industry for many years. The line pressure probes generally report on the line pressure to a central monitor which utilizes the pressure data to provide warning of line leaks and to shut down pumps on lines that are leaking. Such pressure probes have become an essential part of a hydrocarbon storage and dispensing facilities since even very small leaks can result in the loss of thousands of dollars of hydrocarbon, and because spills from leaks have become highly regulated and expenses of cleanup can be enormous.
Up to now most line pressure probes have consisted of line pressure switches which provide a signal if line pressure falls below a certain value, for example, 5 psi. These probes are susceptible to providing an erroneous leak indication when the pressure drop is due to temperature contraction. More recently line pressure probes which provide a continuous pressure reading and also provide the ground temperature have been available. Such probes allow the central monitor to analyze the pressure and temperature data to provide a more reliable indication of whether a leak has occurred. However, many such probes can overwhelm a central monitor with data so that it is slow in responding to leaks, which can be a serious disadvantage that can result in large spills that occur when pumps are not shut down immediately when catastrophic damage occurs in a hydrocarbon storage and dispensing system.
Since the line leak detectors turn off the pumps, repairing pipes on testing repairs for leaks can be difficult unless the system is turned off. Some systems provide a manual reset switch on the central monitor to avoid such problems. However, such resets apply to all probes in the system and can be misused by attendants who reset the system either unintentionally or intentionally when leaks are present.